The invention relates to a drive system for a multi-point forming press.
Known according to DE 10 2004 009 256 is a mechanical multi-servo-press in which the servo-motors with associated pinions as a single-stage gear at spaced apart locations each drive an eccentric wheel for driving a slide having two pressure points. At great pressing forces, high torques for the servo-motors are necessary due to the limited transmission ratio of the single-stage gear. In this regard, the document discloses that the load on the servo-motors can be reduced by using the momentum of the mass moment of inertia of the gear. Since this effect can only be used at elevated speeds, at low speeds the servo-motors would be underdimensioned for applying the installed pressing force, especially in set-up mode.
The intermediate gears that connect the eccentric wheels and that are also necessary for mechanical synchronization in the gear result in increased complexity.
Brake motors are suggested for braking and stopping the slide. Due to the limited transmission ratio of the single-stage gear, elevated braking torques are necessary, which increases the mass moment of inertia. Not disclosed are means required for attaining a safety category necessary for press operation, including possible locking of the slide.
Known in accordance with WO 2004/056559 is another pressing device having a pressure point, in which device a direct drive, in the form of a frequency-controlled AC motor, which is arranged directly on the eccentric shaft, controls the movement of the slide. The limited available torques of the servo-motor enable relatively low pressing forces without any intermediate gearing.
For operational on/off movements for the press device, emergency off devices are provided via the motor control and/or mechanical devices, but the structure required for satisfying safety requirements and their functions is not disclosed.
JP 2006061974 describes a drive system for a multi-point forming press, each of the crank wheels of which can be driven via a two-stage transmission by means of a separately controllable servo-motor, the first gear stage being embodied as a flexible drive, the traction means of which have different lengths between the front and rear pressure point group in a four-point press.
In another multi-point forming press in accordance with JP 2005271070, each drive wheel separately associated with each pressure point and connected to a crank is driven via one or two single-stage toothed wheel gears by a servo-motor, in the case of a four-point press it being possible for the drive for the two drive wheels belonging to one pressure point group to come from one or alternatively two common single-stage gears.
The last two documents cited do not disclose means required for attaining a safety category necessary for press operation, including possible locking of the slide.
Known from DE 199 32 990 is a slide locking and slide release device, for a conventional mechanical press equipped with a flywheel and a clutch/brake combination, in which device a non-positive fit additional brake that is controlled independently of the main brake is arranged on a central shaft, the function of which is monitored cyclically and redundantly for satisfying safety requirements and is integrated into the press safety control unit.
Known from DE 199 10 965 is another locking device for a press slide, in which device the stepless locking of a main drive shaft, which where necessary acts on a plurality of slides simultaneously, is attained using outer and inner teeth that can be caused to engage by means of a positioning device.
DE 101 35 663 describes a positive fit mechanical restraint device that is on a brake device and in which a gear ring is borne rotation-fast in the mutual guide of the outer disks of a multi-disk brake and can be longitudinally displaced in a counter-gear ring, said counter-gear ring being able to perform a rotary movement for positive-fit coupling.
None of these last three publications cited discloses applications in servo-presses that are largely free of flywheels and clutches.
Known from DE 102 44 318 is a press having a servo-spindle drive, the drive movement of which can be braked using a brake motor and/or using a mechanical brake device.
JP 2003290997 discloses a single-point forming press, the drive wheel of which is connected to a crank and can be actuated via a single-stage gear by a servo-motor, a brake borne on the frame side being provided between the servo-motor and the drive wheel.
The measures of the last two publications cited are not adequate for satisfying engineering and personnel safety requirements for presses in order to be classified in a defined safety category.